Rotor & Exciter Tests

DC Winding resistance and AC Impedance Measurement

The rotor DC winding resistance and AC impedance is measured to check for electrical unbalance due  to shorted turns or open circuit faults in the winding. Low resistance Micro-ohmmeter is used for winding resistance measurement where 10 amps DC current is applied and resistance is measured. To measure Impedence AC voltage is applied and current is measured.

Test on Exciter and PMG Machine

The following tests are conducted on exciter armature/field windings PMG stator/rotor windings.

  1. Winding resistance and impedance
  2. IR and PI at low voltages

Miscellaneous Tests

Diode and Fuse checks

A diode is reverse-biased when the positive (red) testlead is on the cathode and the negative (black) testlead is on the anode. The reverse-biased voltage of a good diode displays ‘OL’ on a multimeter. The diode is bad if readings are the same in both directions.